In the known way, a transmission belt drives an outer rim of an alternator pulley which itself drives an input shaft of the alternator. In service, this pulley is subject to variations in speed and torque, notably because of the acyclic operation of the internal combustion engine of a motor vehicle. There are various ways for smoothing out these variations in speed and torque, for example by fitting a one-way clutch (OWC) device, also referred to as a “free wheel” between the hub and the rim of such a pulley. In one direction of rotation, the one-way clutch device transmits torque from the rim to the hub of the pulley, whereas in the other direction of rotation the hub is not driven by the rim.
FR-A-2 726 059 describes a mechanical system of this type in which a free-wheel clutch comprises wedging rollers which are guided in a cage and wedged against wedging ramps formed at the periphery of a ring. Thus, the wedging rollers of the free-wheel clutch interact successively with the wedging ramps of the ring. This prior art dictates the use of a ring provided with ramps, which entails relatively complex operations forming these ramps, requiring qualified personnel and elaborate equipment, resulting in a high cost price. Furthermore, the maximum torque that can be transmitted with this kind of device is relatively low.
These are the disadvantages that the invention more particularly intends to overcome by proposing a novel mechanical system with one-way clutch that allows effective transmission of torque, in one direction of rotation, and freewheel operation in the other direction of rotation, while at the same time offering attractive robustness and an attractive cost price.